Syzeuctus siamensis, Riedel, 2022

Riedel, Matthias, 2022, Contribution to the knowledge of Oriental Syzeuctus FÖRSTER (Hymenoptera, Ichneumonidae, Banchinae), with description of six new species, Linzer biologische Beiträge 54 (1), pp. 257-273 : 269-270

Syzeuctus siamensis nov.sp. ( figs 2 , 9 , 15 , 21 )

H o l o t y p e: (♀) Thailand: N. Pai, 24.V.2018, leg. M. Snizek (Linz). P a r a t y p e: (♀) labeled as the holotype (coll. RIEDEL).

D e s c r i p t i o n: ♀: Body length 16-17 mm. Length of fore wing 10 mm and of ovipositor 10.5 mm. Antenna with 50-52 flagellomeres, filiform; 1 st flagellomere 5.3× longer than wide and 0.77× as long as eye; preapical flagellomere 1.1× longer than wide. Temple short, strongly and roundly narrowed behind eye, dorsally 0.3× as long as eye. OED 1.5× and OOD 1.4× ocellar diameter. Vertex and frons coarsely and densely punctate. Frons swollen laterally and concavely impressed medially. Face densely punctate, inner eye margins parallel. Clypeus 2.0× wider than long, apical margin rounded. MI 0.8. Mandible with baso-ventral lamella, mandibular teeth equally sized.

Mesosoma coarsely and densely punctate, covered with brownish setae, 1.65× longer than high. Frontoventral edge of pronotum moderately curved. Side of pronotum densely punctate, pronotal groove smooth. Epicnemial carina low, pleural part reaching center of mesopleuron, transversal part absent. Mesopleuron densely and coarsely punctate, speculum punctate. Pleural carina absent. Apical transverse carina of propodeum entirely absent. Legs slender; hind femur 5.6× longer than wide. Hind metatarsus 0.87× as long as hind femur. 2 nd hind tarsomere 1.65× as long as 3 rd one. Hind claw with c. 7 short teeth, moderately bent apically (c. 45°).

Areolet with long stalk (stalk about as long as areolet); vein 2m-cu reaching areolet in its distal 0.8. Vein 1cu-a slightly postfurcal by 1× its width. Postnervulus intercepted behind its middle. Hind wing with 9 distal hamuli.

Metasoma slender, tergites with narrow spiracles, spiracles not bulging. 1 st tergite 2.1× longer than wide, largely smooth, with fine pnctures laterally and fine dense punctures in apical 0.1-0.2, strongly shining. 2 nd tergite 1.5-1.6× longer than wide, with dense rather coarse punctures, ± shining. 3 rd tergite 1.2-1.3× as long as wide, with very dense and fine punctures and ± dull. Ovipositor 1.05× as long as fore wing, 1.05× longer than metasoma and 2.0× longer than hind tibia.

Color: Black. Flagellum black. Palps, spot of mandible and apical 2/3 of clypeus reddish. Small spot on frontal orbit and spot on upper outer orbit yellow. Mesosoma black. 1 st to 6 th tergites dark red, 7 th tergite and hypopygium blackish. Sternites ochreous. Coxae and trochanters black, fore coxa entirely and large spot on mid coxa yellow. Femora and tibiae reddish, tarsi brownish. Wings hyaline, fore wing with large brown apical spot. Pterostigma dark brown.

♁ unknown.

R e m a r k: This new species belongs to the villosus group sensu CHANDRA & GUPTA (1977) and runs to S. villosus (CAMERON, 1899) in their key. It differs by the longer ovipositor, absent posterior transversal carina of propodeum and entirely red 1 st and 2 nd metasomal tergites.

Figures

Figs 1-3: Habitus from dorsal: (1) Syzeuctus laoticus nov.sp. ♀ holotype (HT); (2) S. siamensis nov.sp. ♀ HT; (3) S. orientalis nov.sp. ♁ paratype (PT).

Figs 4-9: Basal tergites from dorsal: (4) Syzeuctus achterbergi nov.sp. ♀ HT; (5) S. floresiensis nov.sp. ♀ HT; (6) S. genator nov.sp. ♀ HT; (7) S. laoticus nov.sp. ♀ HT; (8) S. orientalis nov.sp. ♁ PT; (9) S. siamensis nov.sp. ♀ HT.

Figs 10-15: Faces from frontal: (10) Syzeuctus achterbergi nov.sp. ♀ HT; (11) S. floresiensis nov.sp. ♀ HT; (12) S. genator nov.sp. ♀ HT; (13) S. laoticus nov.sp. ♀ HT; (14) S. orientalis nov.sp. ♁ HT; (15) S. siamensis nov.sp. ♀ HT.

Figs 16-21: Heads from frontal: (16) Syzeuctus achterbergi nov.sp. ♀ HT; (17) S. floresiensis nov.sp. ♀ HT; (18) S. genator nov.sp. ♀ HT; (19) S. laoticus nov.sp. ♀ HT; (20) S. orientalis nov.sp. ♁ HT; (21) S. siamensis nov.sp. ♀ HT.